https://github.com/gaugo87/PIXEstL

PIXEstL is a free open source program for creating color lithophane and pixel images. The program relies on a color palette that can be customized by adding its own filaments. This allows for the creation of lithophanes with an infinite variety of filaments.

The filaments can be added to the palette in two ways:

For example for lithophanes, in addition to the usual Cyan, Magenta, and Yellow filaments, the palette allows for the addition of Black (for achieving deep black), or simply adding lighter CMY shades (in addition to the usual ones) to enrich the color palette.

Most of these creations were printed with 7 filaments.